Tribune Investigative Task Force member William Mullen uncovered evidence of widespread election fraud in the March 21 presidential primaries in Chicago while working undercover as a clerk in the Chicago Board of Election Commissioner's City Hall office.

James O'Keefe and Hannah Giles posed as a pimp and a prostitute for an undercover camera investigation. Some low-level employees of the organization provided earnest answers to the pair's questions about avoiding detection and tax evasion, among other things. Fox News and Andrew Breitbart's Biggovernment.com (which was launched with these videos) helped to push the story beyond conservative media outlets and draw attention to the pair's findings. As a result, and after considerable media attention, ACORN was defunded by Congress.

O'Keefe secretly recorded a conversation between NPR's Ron Schiller and two of O'Keefe's partners, posing as representatives of the "Muslim Education Action Center." The video, which was later revealed to be heavily edited, contained a number of instances of Schiller allegedly calling the Tea Party racist and Islamophobic.